Vitality and Organization of Protoplasm. 17 



self-division, transmitted in its developed and developing condition to 

 every cell, and is therefore continuous in phylogenetic as well as onto- 

 genetic evolution, lii lower plants every cell has complete reproductive 

 power. In Jiigher plants and in higher animals this power of repro- 

 ducing the entire adult organism is, however, delegated to special germ- 

 cells. 



According to Xaegeli's views, the idioplastic substance consists at 

 every stage of phyletic development of single filaments of equal and 

 equally oriented micellar groups. These filaments are believed to grow 

 lengthwise by self-division of their micellar groups. In the course of 

 further phyletic evolution, filaments whose micellar groups have become 

 differentiated arc developed alongside the primitive filaments, so as to 

 form fasciculse of diversely constituted micellar groups. In complex 

 organism correspondingly complex strands of such filaments ramify in 

 form of a network throughout the entire organism. These complex 

 strands grow, as such, lengthwise through self-division of the micellar 

 groups of which they consist. Each cross-section of idioplasm comes 

 thus to contain a full assortment of micellar groups, and constitutes 

 thus the "Anlage" or collective germ of the differentiated cells and 

 tissues, to whose formation they give rise in the course of ontogenetic 

 evolution. 



With Naegeli propagation, the supreme vital phenomenoa, is — as 

 with Haeckel — merely mechanical division of overgrown groups of ele- 

 mentary units formed by the intussusception of more f^nd more numer- 

 ous like elements. To account for self-division of the germ-cell into 

 an increasingly differentiated progeny, Naegeli does not, like Haeckel, 

 endow his elementary units with a reproductive memory, acquired 

 through unlike ontogenetic exposure to differentiating external condi- 

 tions. He attributes organic evolution, with its increasing complexity 

 of micellar structure and differentiation of vital functions, to an in- 

 trinsic tendency of the combining molecular forces of the idioplastic 

 micellar groups to give rise to the formation of higher organic beings; 

 and he maintains that evolution once started in a given direction tends 

 to continue in the same. 



jSTaegeli's answer, then, to the first question, which arises when or- 

 ganic reproduction is contemplated from the standpoint of the cell- 

 theory ; the question, namely,, how a self-dividing elementary organism, 

 such as the germ-cell is conceived to be, comes eventually to propagate 

 the differentiated progeny which constitutes the variform tissues of 

 higher organisms; — his answer to this vexed question consists in an 

 elaborate, but vain, attempt to apply mechanical conceptions to the vital 

 phenomena here involved. Naegeli's vital units, the micellae, of which 

 the entire organism is said to be composed, are mere crystals of organic 

 matter possessing no trace of what really constitutes vitality. Intus- 

 susception of new micellae into groups already formed, causing mere 

 increase of their bulk, which he misnames "growth;" such mere aggre- 

 gation of organic crystals can not rightly be considered a vital phe- 



